Age resistor for rubber



Patented July 11, 1944 UNITED" STATES PATENT" OFFICE Winfield S'co'tt, Akron, Ohio, assignor to wing foot Corporation, Wilmington,.Del.,. a corporation ofD'elaware Nd-mating; ApplicationAugust-28; 1940;

. i ,j fS rialNo. 354,519:

Thisinvention relates to-age-resistorsfor rubber and moreparticularly to the:use-in rubber of aldehyde derivatives of terpenyl arylamines;

Many substancesare known to prevent or retard the deterioration of rubber which is normally' caused by the action-of: oxygen, light, heat. flexing I and other influences, suchpreservative:

materials commonly being designated. as anti.- oxidants or age-resistors. The choice of an ageresistor in a given case is largely governed by the'- particular combination of properties imparted by it tothe rubber stock-employed.

According to the present invention, terpenyl a-rylamines prepared by the reactionof terpenes and arylamines are reacted with aldehydes to produce materials whichare excellent age-re:- sistors for rubber.

' W hen" a terpene is reacted with aprimary or secondary arylamine, preferably inthe presence of 'acatalyst such as zi'nc chloride, hydrochloric acid or iodine anaddition productis formed which may be called-a terpenyl. aryl'amine. The

preparation of such materials and their usein rubber are described in U.- S. Patent-No.2 ,180,- 936* and S. Patent No.- 2-, 1-89g736.- A

- It has-now been discovered thatterpenyl arylamines may be further reacted with aldehydes, With the eliminationor water, to produce condensation productswhich are very efl ective a'geresistorsfor rubber.

The preparation of the: age-resistors ofthe; invention is illustratedbythe following example Example Fifty-sevengrams of; pinyl. aniline lthe. addition: product of equimolecular proportions of. anilineand-pinene) ,.5 cc. of concentratedhydrochloric acid and. 50 grams of alcohol were mixed. until. the: solution was homogeneous. Eighteen grams of. crotonaldehyde. were thenadded and.

an: exothermic reaction. took place, causing a temperature rise of. 17 The mixture. was: re:-

fluxed. for about. one hour and was then poured into water to precipitateth .product. .Thewater suspension was treated with ammonia. to.neu-- tralizeathe. hydrochloric acid. present; and. the

product. was recovered as a soft,.-b1ack resin The:

yield'was 97% *of the theoretical.

Various other terpenyl arylamines may beiused in. place of. the plinyl aniline of the. foregoing example. In preparing theseterpenyl arylam-ines'; any terpene may be employed, including both cyclic and olefinicterpenes.- The mono"- cyclicand dicyclic terpenes are preferred materials. Further representative examples of suitable terpenes are dipentene, limonene, terpinolene, phellandrene, menthadiene, sylvestrene'terpinene, santene, etc.- Also, variousnatural products, such as turpentine and'camphor' oil, which contain substantial amounts of terp'enes may be employed. Similarly, any primary or secondary arylamine may be used in preparing the terpenyl arylamine, including aniline, the naphthylamines, p-phenylene diamine, diphenylamine.

phenyl-fi-naphthylamine, phenyl-a-naphtl'i yl amine, N-methyl anliline, N-cyclohexyl-p-naph thylamine, etc. Aniline and diphenylamine give good results, are cheap, and constitute a preferred gr0up.- Also,- eitherthe terpene or the arylamine may contain one or more substituents such as alkyl, aryl, aralkyl, alkoxy, aryloxy and:

' dehyde, tetrahydrofurfuraldehyde; naphthaldehyde, furyl'. acrolein, etc.. The aliphatic aldehydes, including saturated and unsaturated,

straight and branched chain,- cyclic. and ringsubstituted aldehydes, constitute a preferred class.

The reaction between the aldehyde and the terpenyl arylamine is quite complex. For. x.-

ample, when, the latter is secondary. amino:- in character,. the amino hydrogen atom is'repla'ceable and the aldehyde may react at that. In addition, the aldehyde may react. in: the aryl nucleus. usually. ortho or para .to the amino group. It, isalso possible: that other: reactionsmay take place. .As. a. result. of. the complexity,

of the reaction, the proportions of aldehyde and terpenyl arylamine are not critical but may be varied within wide limits. Ordinarily, about one-half to two mols of aldehyde will be used for each mol of terpenyl arylamine employed. Equimolecular proportions are preferred. If an excess of either reactant over the amount which will react is employed, the excess merely carries through to th product as an impurity, which may be removed or not according to the requirements of each case.

The temperature of reaction is not critical but will ordinarily lie, between C. and 150 C. Inasmuch as various aldehydes have different reactivities, the temperature employed will depend in part upon the choice of starting materials. temperature and in a shorter time than will aethyl-p-propyl acrolein. 5

The reaction is preferably carried out in the presence of an acidic condensation catalyst, of

which a number are well-known. Representa- Y tive examples are zinc chloride, iodine, hydror. chloric acid, hydrobromic acid and phosphorus Ordinanily, these catalysts are employed in relatively small amount. However, I

pentachloride.

if afree acid .such as hydrochloric acidis used, an amountof acid suflicient to form the salt of the terpenyl arylamine may be desirable in some cases.

The efiicacy of the materials was tested by milling the age-resistor into rubber in accordance with the following formula, curing test samples and determining the physical characteristics thereof before and after ageing for six days under an oxygen pressure of 150 pounds per square inch and at a temperature of 50 C.

The following"representative data were obtained using the product of the example.

Thus, formaldehyde will react at a lower I When the product of the example was incorporated into rubber in accordance with this formula and samples were cured and tested before and after ageing for seven hours at an air pressure of 80 pounds per square inch and at a temperature of 114 C., the following results were obtained:

re Tensile, Ult. elong. Cure in m1n./F. kEI/Om'Z in per cent BEFORE AGEING As demonstrated by these data, the age resistors are very efiectivein retarding the deterioration of rubber, both at low and high temperatures.

While there have been described above certain 30. preferred embodiments of the invention, the same is not limitedthereto but only by the appended claims wherein it is intended to set forth all features of patentable novelty residing in the invention.

I claim: 4

1. A method of treating rubber which comprises vulcanizing the same in the presence of the condensation product of an aldehyde and a terpenyl arylamine produced by the reaction of a terpene 49; with an amine selected from the group consisting Ult l i i 1 e g. cm. er cent Cure in min./F. fi g in g increase y percent in weight BEFORE AGEING AFTER AGEING The characteristic's on high temperature ageing were-tested in the following formula:

Age resistor of primary and secondary arylamines. J 2. Amethod of treating rubber which comprises vulcanizing the same in the presence of the product obtained by reacting, in the presence of an ;acidic condensation catalyst and at a temperature of about 25150 0., an aldehyde and a terpenyl arylamine produced by the reaction of a terpene with an amine selected from the group consisting of primary and secondary arylamines. 3. A method of treating rubber which comprises vulcanizing the same in the presence of the condensation product of an aldehyde and a terpenyl arylamine produced by the reaction of a terpene with a primary arylamine.

4. A method of treating rubber which comprisesvulcanizing the same in the presence of the condensation product of an aldehyde and a terpenyl arylamine produced by the reaction of a terpene with a secondary arylamine.

' 5.v A method of treating rubber which comprises vulcanizing-the same in the presence of the condensation product of an aliphatic aldehyde and a terpenyl arylamine produced by the reaction of a terpenewith an amine selected from the group consisting of primary and secondary arylamines.

6; A method of treating rubber which comprises densation product oficrotonaldehyde and pinyl.

1.00 8. Arubber productwhich hasbeen'vulcanized in the presence of the condensation product of an aldehyde and a terpenyl arylamine produced by the reaction of a terpene with an amine selected from the group consisting of primary and secondary arylamines.

9. A rubber product which has been vulcanized in the presence of the product obtained by reacting, in the presence of an acidic condensation catalyst and at a temperature of about 25-150 C., an aldehyde and a terpenyl arylamine produced by the reaction of a terpene with an amine selected from the group consisting of primary and secondary arylamines.

10. A rubber product which has been vulcanized in the presence of the condensation product of an aldehyde and a terpenyl arylamine produced by the reaction of a terpene with a primary arylamine.

11. A rubber product which has been vulcanized in the presence of the condensation product of an aldehyde and a terpenyl arylamine produced by the reaction of a terpene with a secondary arylamine.

12. A rubber product which has been vulcanized in the presence of the condensation product of an aliphatic aldehyde and a terpenyl arylamine produced by the reaction of a terpene with an amine selected from the group consisting of primary and secondary arylamines.

13. A rubber product which has been vulcanized in the presence of the condensation product of an aldehyde and a terpenyl arylamine produced by the reaction of a terpene with a diarylamine.

14. A rubber product which has been vulcanized in the presence of the condensation product of crotonaldehyde and pinyl aniline.

WINFIELD SCOTT. 

